These are polyurethane polyester foam strips which are impregnated with various sealing tacky compounds (butyl, PIB...) in order to have a sealing tape which must be compressed between the parts to be sealed.
It is used for sealing of prefabricated concrete panels, curtain walls, installation of windows (wood, aluminum, or PVC), wood panels.
Back-up materials are usually foam strips round or rectangular sections which are inserted at the bottom of the joints, before application of the sealant. This has 2 purposes:
To control the depth of the sealant in the joint
To provide support for the sealant in horizontal joints
The sealant should not stick to the backup material and the solvents of the sealant should not affect the backup material.
Back-up materials are usually polyurethane or polyethylene foams, sometimes neoprene foams, and other materials.
Foams may be open cells or closed cells: the choice between these two depends on the type of sealant used and the job site conditions. Users will refer to the sealant supplier for advice.
